Israeli and Lebanese forces briefly exchanged fire across the border today, killing an Israeli officer, three Lebanese soldiers, and a Lebanese journalist. The conflict has sparked tension on both sides of the border and raised fears of a return to the periodic Israeli-Lebanese violence that most recently recurred in Israel's 2006 invasion in retaliation against Lebanon-based militant group Hezbollah.

• How It Probably Started  Ha'aretz's Jack Khoury explains, "Since the end of the Second Lebanon War, the IDF has conducted patrols up to the international border, which in some places is on the Lebanese side of the border fence. It is possible that Tuesday's incident was caused by one of the sides misidentifying the correct location of the border. In Lebanon, there was a report that Lebanese soldiers had demanded that Israeli troops leave the area before the exchange of fire took place. ... 'It started when the Israelis wanted to cut a tree down inside Lebanon,' one security source in Lebanon said. 'The Lebanese army fired warning shots at them and they responded by shelling.'"

• Why Was Israeli Officer Cutting Trees?  Al Jazeera's Gregg Carlstrom is skeptical. "I must say I am a little curious to know why the Israelis had a lieutenant colonel 'cutting down trees' along the Lebanese border," he muses. "Clearing brush is awfully low-level work for a high-ranking officer." Other reports say that Israeli troops were installing security cameras.

• Dispute Over 'Blue Line'  The New York Times' Isabel Kershner reports, "Israel said its forces were engaged in routine maintenance work in a gap between the so-called Blue Line, the internationally recognized border, and its security fence, and that it had pre-coordinated its activity with the United Nations peacekeeping force in South Lebanon, Unifil. ... But the Lebanese president, Michel Suleiman, said Israeli troops had crossed the Blue Line and fired on a Lebanese army checkpoint in Adeisseh."

• 'Warning Shots' Rapidly Escalated  The L.A. Times' Edmund Sanders writes, "Lebanese soldiers said they fired warning shots at the Israelis, prompting a brief but heavy exchange of fire. Israeli military officials said they returned fire with light arms and artillery and then dispatched helicopters several minutes later to attack a Lebanese command center, damaging several armored combat vehicles. Officials for the U.N., which has dispatched 12,000 peacekeepers to monitor the area, has called for restraint."

• War of Words Begins  The Jerusalem Post's Yaakov Katz reports, "Lebanese President Michel Suleiman called on his country to 'stand up to Israel's violation of UN Resolution 1701 - whatever the cost.' Resolution 1701 brokered the cease-fire which ended the 2006 Lebanon War. ... The [Israeli] Foreign Ministry released its own reaction Tuesday, saying that it was Lebanon who had committed harsh violations of Resolution 1701. Foreign Minister Avigdor Lieberman instructed Israel's UN representative to submit a complaint to the UN secretary general and security council, saying that Israel holds the Lebanese government responsible for the very serious incident."

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